DE3042819A1 - CIRCUIT ARRANGEMENT FOR SUPPLYING A SYNCHRONOUS MOTOR FROM A DC VOLTAGE NETWORK - Google Patents

Description

R. 666 4

October 28, 1980 Lr / Wl

ROBERT BOSCH GMBH, TOOO Stuttgart 1

Circuit arrangement for supplying a gynchror motor from a DC voltage network

The invention is based on a circuit arrangement according to the preamble of the main claim.

Synchronous motors are usually fed from an alternating voltage network, with the three-phase winding fed by the Hetz generating a rotating field which entrains the rotor's pole system. The rotor's pole system is either fed with direct current via slip rings or is designed as a permanent magnet system the publication "Intermetall, 100 typical circuits with semiconductor components", Freiburg 1 ^Q 67 »Example Mr. 30 a three-phase generator without a transformer known, as it can be used in connection with synchronous motors if the speed of locally separated drives is exactly the same and also variable This enables the realization of a so-called "electric wave"

Build up "electric gearbox" with it, -if the frequency with which the first generator is controlled is electronically reduced, and thus a second one Generator controls. Drives with a fixed speed ratio are then obtained.

However, the known circuit arrangement does not disclose any means for cyclically advancing the stator windings of the synchronous motor. In addition, there are problems with starting the motor, current limitation and speed control not taken into account.

The circuit arrangement according to the invention with the characterizing Features of the main claim has the advantage that the switching of the stator windings is controlled by the position of the rotor, so that d ° r Synchronous motor behaves like a permanent magnet DC motor.

Through the measures listed in the subclaims Advantageous developments of the circuit arrangement specified in the main claim are possible.

In this way, the connected winding is divided by the number of phases during an electrical angle of 360 of the motor is switched on, which is symmetrical to the apex of the negative half-wave of the induced alternating voltage lies. As a result, the synchronous motor delivers its maximum torque and has the highest degree of efficiency.

By using a ring counter for cyclical indexing of the stator windings with a clamping circuit at the counter input it is achieved that when switching over

if
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Interference signals occurring in the stator windings do not affect the indexing of the ring counter.

Furthermore, in "preferred embodiments of the invention Schaltungsnaorndung means are provided which "cause a start-up current limitation", as well as others Means that enable speed control of the synchronous motor.

In the drawing are exemplary embodiments of the invention shown. Show it:

Figure 1 shows the schematic diagram of a synchronous motor Switching valves in the feed lines of the stator windings;

Figure 2 shows the circuit diagram of an electronic circuit arrangement for cyclic switching of the stands winding up;

FIG. 3 shows different signal curves as occur in the circuit arrangement according to FIG. 2;

FIGS. H to 6 circuit diagrams of circuit arrangements for limiting the starting current of the synchronous motor;

Figure T shows the circuit diagram of a circuit arrangement for Current limitation and speed control of the synchronous motor;

FIGS. 8 and 9 circuits for a control device with improved start-up behavior;

FIG. 10 shows a time diagram for this.

In Figure 1 is the circuit diagram of a circuit arrangement shown, which is used to supply a synchronous motor from a DC voltage network. The synchronous motor is

-χ- R. 66

denoted by 10 "and has stator windings ¥., ¥„, W_, Wi, which are star-connected, the star point being led to a terminal of the DC supply voltage U. The other ends of the stator windings W ₁ , W ₂ , W_, Wi are connected via electrical valves T ₁ , V _p , T-, V. to a collecting line which is connected to the other pole of the DC supply voltage U. The electrical valves V ₃ V ₃ V ₅ V are in the exemplary embodiment shown as transistors according to FIG. 1, the collector-emitter paths of which the control voltages U ₁ , U ₃ U_, Ui are applied when the valve is blocked. Of course, other electrical or electronic switching elements can also be used as valves The illustrated embodiment is designed as a permanent magnet, the poles of which are denoted by N and S.

By cyclically actuating the valves V, V ₂ , V ₅ V, the stator windings W, W _p , W_, Wi can now be connected to the DC supply voltage U one after the other, with one winding being switched on and the other being switched off in the circuit arrangement according to the invention and the switching of the valves V, V, V, V, is carried out as a function of the voltages that result from the difference between the DC supply voltage and the AC voltages induced in the stator windings and as U ₁ , Up ₃ U_, Ui are removable.

An embodiment of a circuit arrangement according to the invention for cyclically switching the stator windings W ₁ , W ₂ , W_, Wi is shown in FIG. The circuit arrangement is on the input side from the voltages U ₁ , U _? , U_, Ui acted upon and supplies control signals on the output side for the valves V ₁ , V ₃₅ V, V ^. The voltages U, U, U ",

- * - * · 66

U. -are fed to positive inputs of comparators 11, 12, 13s I ^, the negative inputs of which are connected to a positive input of another! Comparator so that the voltage U in the first comparator 11 with the voltage U ,, im second comparator 12 the voltage U with the voltage U., in the third comparator 13 the voltage U ^ with the voltage Up and in the fourth comparator ~ \ h the voltage Ui is compared with the voltage U. The outputs of the comparators 11, 12, 13, 1H are _{routed to first inputs of AND gates 15, 16, 1T 5} 18, the other inputs of which are routed to the output control lines for the valves V, V ^, V, V. . The first AND gate 15 with the output control line for V, the second AND gate i6 with that for V ₅ ', the third AND gate 17 with that for V. and the fourth AND gate 18 with that for V. tied together. The outputs of the AND gates 15, 16, 17, 18 are fed to a U-bin OR gate 19, the output of which is connected to an input of an AND gate 20. The output of the AND gate 20 is connected to a dynamic set input of a monostatic flip-flop 21, which has the service life t "... The non-inverting output of the monostable multivibrator is connected to the further input of the AND gate 20 via an inverter 22 and also to the dynamic counting input 230 of a counter 23. The counter 23 has four counter states corresponding to the number of phases η = U of the synchronous motor 10 shown in FIG. Each counter status 1 to k generates a signal on one of the counter output lines 1 to U, with output line 1 with the control input for valve V ₁ , output line 2 with that for valve V, output line 3 with that for valve V_ and the output line h is connected to that for valve V. Each time input 230 is activated, the counter is moved one digit in the order 1-2-3 - ^ - 1

iZ

-j6- κ. 6 6

continued and the control of the. Valves are thus switched on in the same order.

The mode of operation of the circuit shown in FIG. 2 will now be explained with reference to the diagrams shown in FIG. FIG. 3a shows the _{voltages U 1} , U _{? Induced in the stator windings W 5} Wp, W_, Wi. , U_, Ui, which occur if a stator winding would not be connected. In order to utilize the maximum torque and the highest efficiency of the synchronous motor, according to the invention each winding is switched on at an angle of 90 (for a four-phase motor) symmetrically to the apex of the negative half-wave of the induced alternating voltage, i.e. to the minimum of the voltages U, U, U, U . From FIG. 3a it follows immediately that, for example, the start of connection for the stator winding W ₁ coincides with the point in time at which the voltage U_ is greater than U _? will. Correspondingly, from the first winding W ₁ to the second winding W _? to switch on when the voltage Ui is greater than U_. Generally speaking, in an n-phase synchronous motor (n even), the i-th winding is switched on and the (ii) -th winding is switched off when

^ü i ₊ | > ^ü i ₊ f - 1

where U. denotes the voltage induced in the i-th winding and i = i + k. η for k = 0,1,2 ... is (example: η = k , connection of Wi if Uy- "> U or with k = 1 if U _g > U ₁ ).

This is expressed in FIG. 3b, where the respective state Z of the counter 23 is plotted. As can be seen, that is

-x-

66 64

Control signal linked to the counter reading "i" during the aforementioned connection period for the winding W _1. When the voltage U> is greater than U ", the counter goes into state 2, whereby the valve V is actuated in accordance with the circuit according to FIG.

As mentioned, the advancing of the counter 23 is effected by triggering the input 230 via the non-stable multivibrator 21 ". For this purpose, the switching conditions are first set in the comparators 11, 12, 13, 1U according to a comparison of the voltages U, U, U, U, and "when a switching point is reached," for example, when U_ is greater than Up, at the output of the! Comparators 13 a control signal to the AND gates 15, 16, 17, 18, in the example the AND gate 17 »passed on. The AND gate 17 then switches through when the state "V" is written into the counter 23 at the same time, which, as FIG. 3-b shows, is the case _{before the switching condition U is greater than U?} 17 j 1 "8 with the counter _{output signal a preparation of the AND gates 1 5 5} 16, 17, 18 is effected in such a way that a signal for switching the counter via the AND gates 15 ₅ 16, 17» 18 is only passed on is when, on the one hand, the counter 23 was in the previous counter and, on the other hand, the switching condition defined from the voltages U., U, U .., U- has been reached.

Each of the output signals of the AND gates 15 »1 6 a 17s 18 controls an input of the AND gate via the OR gate 19 20, which in turn is due to the tax input of the

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monostable flip-flop 21 acts. Linking the
non-inverted output of the monostable multivibrator
21 via the inverter 22 to the other input of the
AND gate 20 has the meaning of the input 230 of the
To keep counter 23 for the duration of the service life of the monostable multivibrator 20 on a positive signal, such as
this is shown in Figure 3c. This has the effect that the interference voltages occurring when the windings are switched over do not lead to an unintentional further switching of the counter 23 before the next defined switchover condition is reached. FIG. 3c represents the output voltage at the non-inverted output of the monostable multivibrator 21, the service life being denoted _{by t v1.} This service life is measured in such a way that all
Settling processes after switching the stator winding w / Uircml 'IrT nt.find v.ri t iilifrpkiunßen are and the monontabilc-Ki 14'IiIuIV ..' 1 and damil. the counter 'di can be released for the next switching process.

Figure 3d, 3e, 3f, 3g show the output terminals
for the valves V, V, V_, V> pending control signals. In the example mentioned above, in which a switch is made to the stator winding W when U_ is greater than U ₅ , this means that until the next one is reached
Switching condition (U, greater than U) the valve V remains activated. Then it is switched to V, then to V and so on.

Finally, FIG. 3h shows the voltage, for example
U is shown for the stator winding W ₁ , with the stator windings being switched on and off in contrast to FIG. 3a. This means that to connect

BATH ORIGINAL

κ. 66

At the time of the stator winding W _1, the voltage U drops to zero because of the activation of the valve V until the stator winding W is switched on. As explained further below, it is possible in an advantageous embodiment of the circuit arrangement according to the invention _{to delay the connection time for the individual windings, in the example shown for the stator winding W 1} by a predeterminable amount of t "_, in order to enable speed control of the To effect synchronous motor.

In the synchronous motor operated according to the invention builds As with a DC motor, a counter-voltage that increases with increasing speed occurs, so that the current decreases. If you want to dimension the switching elements for the current at a higher speed, it is necessary to to limit the current in the start-up phase of the motor.

In a first development of the circuit arrangement according to the invention (FIG. K) , a series resistor 2k, known per se, is connected to the feed line of the star point of the stator windings W ₁ , W ", W ~, W <, as shown in Figure k . The series resistor 2h can be bridged with an electromechanical or electronic switch 25 either as a function of the current or the speed.

According to a further embodiment of the circuit arrangement according to the invention (Figure 5) the synchronous motor 10 is connected to the tap of a voltage divider, which consists of a Longitudinal element 26 and a capacitor 27 consists. The adjustable series element 26, for example a series transistor, the voltage U and thereby indirectly the motor current is limited. The capacitor 27 is used in this

ro - R.

66

Execution form to compensate for those in the freewheeling phases To ensure occurring peaks and thus an overall improvement in the efficiency of the synchronous motor "cause ·

Finally, FIG. 6 shows an embodiment of one according to the invention Circuit arrangement shown in which the Gloichr.voltage for feeding the. Synchronous motor 10 from a AC voltage U- ^ is obtained, the supply DC voltage U can be set at the capacitor 27 by a controllable rectifier 28.

The starting current can be limited by clocking the valve V, V, V, V, which is controlled by the counter 23, and thus, for example, limiting the maximum value or the mean value of the current. If one proceeds in this way, however, a reliable comparison of the voltages U _a U, U, U, is no longer possible due to the pulsing. ' For this reason, the pulsing must be stopped shortly before an expected intersection of the voltage values. In Figure T, an arrangement is shown in which both the starting current can be limited by clocking and the speed of the synchronous motor 10 can be adjusted. For this purpose, the control signal for a valve V is converted into a modified control signal V. The control signal V can be taken from the output of an AND gate 30, the inputs of which are connected to an AND gate 31 or an ODEE gate 32. On the input side, the AND gate 31 is connected to the control signal for the valve V, on the one hand, and to the inverted output of a monostable of a monostable multivibrator 33, which has a service life t _v that depends on the difference between a target

BATH ORIGINAL

30A281S

-Λ η. ⁶ 6

Speed η.,., And an actual speed η. , is adjustable, should, is

as indicated by the sum point 35. The input of the OR gate 32 is connected to the inverted output a monostable multivibrator 3 * +, which is controlled by the control signal for the valve V is controlled and connected to the output of a clock device 36, which is dependent on the difference between a maximum current i and an actual current

Max

can be controlled, as is shown by the sum point 37.

In order to limit the current in the manner described above, the difference is first shown at the summation point 37

of actual current i. , and maximum current i formed and in is max

The clock device 36 is controlled as a function of this difference. The control signal for the valve V sets the laonostabile flip-flop 3 ^ for a predetermined time, which is, for example, 0.8 times the connection time of a winding. Then it is ensured by the combination of the output signals of the elements 3 ^ _s 36 in the OR gate 32 that after the end of the idle time of the monostable flip-flop 3 ^ the OR gate 32 is controlled in any case, ie that the clock device 36 only during a first Part of the connection time of the respective winding becomes effective. This is followed by a settling time in which the transition phenomena caused by the clocking have subsided, so that the ring counter 23 can be prepared for the next step.

In order to set the speed of the synchronous motor 10, it is possible, on the one hand, to either use the longitudinal element 26 according to FIG 5 or the controllable rectifier 28 according to FIG.

- «- β. 6 6 6

type so that the voltage U changes until the desired speed is reached. On the other hand, however, it is also possible to regulate the speed by means of pulse length control. For this purpose, the difference between the actual speed n. And a So]! Speed η _{Ί1 is} formed at the sum point 35 according to FIG. T and the service life of the monostable flip-flop 33 is set as a function of this difference. As long as the monostable multivibrator 33 is in the set state, the control signal for the valves V is not passed on via the AND gate 31 and the AND gate 30. As already mentioned above in the description of FIG. 3h, this delay in the control signal V causes a change in the voltage profile of, for example, U in the manner shown in dashed lines in FIG. 3h. The effective connection time of the stator winding W ₁ in the example is shortened and the speed is reduced accordingly. In the exemplary embodiment according to the figure, the speed of the synchronous motor 10 is regulated on the basis of the comparison of the setpoint and actual speed. However, it is of course also possible to use a control of the synchronous motor 10 instead of a regulation by feeding in a control signal at the summation point 35.

Since when the synchronous motor operated according to the invention is at a standstill If there is no information about the position of the rotor, a special control system is required to start up. For this purpose, according to the invention, either a rotating field is initially very lower, preferably slightly over time generated with increasing frequency and then switched to the self-guidance described in detail above. The switchover can either take place at a certain speed or depending on switching means that

β.

65 6 4

recognize when the induced voltages U ₁ , U _? , U, U. enable position detection. In a further preferred embodiment of the invention, a start-up control is "effected by bringing the rotor into a defined position before starting by switching on a valve for a longer period of time, then switching off the valve and switching on the next valve cyclically at the same time Comparators 11, 12, 13, 1 ^ that the next but one valve is already switched on automatically.

The indirect pole wheel position message described above is based on the comparison of the ones induced by the electric motor Tensions in the windings through which no current flows. E.g. the transistor T. conducts so long until U,> U, then T blocks and T becomes conductive until U> Ui is etc. This recognition of the pole wheel position by Comparison of the phase voltages does not require any additional components on the motor. It works even with very small ones Rotational speeds, but not yet at a standstill. Therefore, special measures are required for the start.

As suggested above, the counter can be started by an auxiliary clock in very slow steps (approx. 0.5 seconds) can be switched so that the runner is safe can align. As soon as direction of rotation, counter reading and If the voltage intersection match, the motor goes into self-control and accelerates with maximum torque except for the operating speed. In the worst case, this arrangement results in a start delay of more than a second.

This start delay is not available for certain applications portable (e.g. for fuel pumps for injection engines)

ε.

An instantaneous start can thereby be achieved according to the invention be that when the motor is stopped, the rotor is brought into a defined position from which a new one Start can be done without delay.

Every starting process requires a certain position of the pole wheel and begins by setting the counter to a certain position and connecting a motor winding to the supply voltage via the corresponding transistor (for example T ₁ , the further course relates to this example). If U-> U within a certain time, T is blocked and T is conductive. As a rule, the motor runs in self-control from the first step. If a certain time is exceeded before Ui> U (standstill due to unsuitable starting position of the pole wheel), or if U "> ■ U, is already immediately after the intersection point U ^!> U_ (backward movement due to unsuitable starting position of the pole wheel), the start-up is interrupted and a positioning process is initiated. During positioning, the transistors T and T are switched on one after the other for approx. 0.5 seconds can.

According to the invention, in preparation for the quick start after each shutdown of the engine (e.g. shutdown of the fuel pump if the combustion engine is activated by the ignition key is switched off) the positioning is carried out in a follow-up program and then the system is switched off.

A new start usually takes place without a start delay.

If the repositioning has been disturbed by any circumstance and the quick start does not work, an additional positioning process is automatically initiated.

In a further embodiment of the invention, the positioning process before the actual start via the ignition key from an additional signal, e.g. seat or Door contact, initiated.

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Claims (1)

3 O Λ 2 8 1 β. 6 ^ 64 October 28, 1980 Lr / Wl ROBERT BOSCH GMBH, TOOO Stuttgart 1 Expectations / 1. ^ Circuit arrangement for supplying a synchronous motor from a DC voltage network, in which the stator windings of the synchronous motor in cyclic order to the DC voltage are switched, characterized in that the alternating voltages induced in the stator windings that are not connected are measured and the connection at least approximately one stator winding during a given electrical angle range symmetrical to the apex of the negative half-wave of the alternating voltage induced in each of the stator windings is made. 2. Circuit arrangement according to claim 1, characterized in that the electrical angular range at a n-phase synchronous motor (10) is 360 / n. 3. Circuit arrangement according to claim 1 or 2, characterized in that that the times for connection and disconnection of the respective stator winding by comparing the in ORIGINAL INSPECTED . ⁶ 664 the voltages induced by the stator windings that are not switched on can be determined. H. Circuit arrangement according to Claim 3, characterized in that in the case of an n-phase synchronous motor (10) (n even-numbered) the i-th winding is switched on and the (ii) -th winding is switched off (i = i + kn for k = 0.1 , 2, 3...; I <η) if U., n ^ U. η where U. denotes the voltage induced in the i-th winding. 5 · Circuit arrangement according to one of the preceding claims, characterized in that _{a counter (23) is used for cyclical switching of the stator windings (W-, W 2} , W, W *) which is dependent on the induced alternating voltages (U, U _p , U, U,) comparing comparators (11, 12, 13, 1M) and its outputs are connected to valves (V, V, V, Vi) that cause the stator windings (W, W, W, Wi) to be switched on and off and on the other hand are connected to switching means with which the output signals of all comparators (11, 12, 13, 1 * 0 except for one are blocked ε. 6664 the one, and the comparator that is not "blocked" the next Counting supplies. 6. Circuit arrangement according to claim 5 »characterized in that the counter input (230) of the ring counter (23) according to each counting pulse is blocked for a predetermined time. 7 circuit arrangement according to one of the preceding claims, characterized in that there is a bridgeable series resistor in the power supply of the synchronous motor (10) (2U) is switched. 8. Circuit arrangement according to one of claims 1 "to 6, characterized in that the synchronous motor (1O) is connected to a tap on your voltage divider (26, 27) is, which is a controllable longitudinal element (26), preferably contains a series transistor. 9- circuit arrangement according to an eier Anr.prücho 1 bin 6, characterized in that the DC supply voltage (ü) of the synchronous motor (10) via a controllable rectifier (28) is obtained from an alternating current network. ' 10. Circuit arrangement according to one of the preceding an. Proverbs, characterized in that the supply-equal-Bparinuiig (U) of the synchronous motor (1O) is clocked. 11. Circuit arrangement according to claim 10, characterized in that the clock ratio by comparing the actual current (i.,) and maximum permissible current (i) is determined max 12. Circuit arrangement according to claim 10 or 11, characterized in that the synchronous motor (10) only during
of a first part, in part 80 %, the connection time of the respective stator winding (W, W _?, W_, Wi) is clocked. 13. Circuit arrangement according to one of the preceding claims, characterized in that the connection time of the respective stator windings (W, W ₂ , W_, Wi) as a function of the difference between the target speed / actual speed
of the synchronous motor (10) is adjustable. lh. Circuit arrangement according to Claim 13, characterized in that the connection time of the respective stator winding (W, W_, W, Wi) is delayed. 15 circuit arrangement according to one of the preceding Claim characterized in that furthermore a Oscillator, preferably of a lower or slightly increasing frequency, is provided, to which the counter (23) can be switched over briefly to start the synchronous motor (10) from standstill. 16. Circuit arrangement according to one of claims 1 "to 1U, characterized in that "when starting up the synchronous motor (10) first a stator winding is statically switched on and then to the cyclically next winding is switched. 17. Circuit arrangement according to one of claims 1 to 16, characterized in that means are provided that "when the rotor is stopped, this into a defined Bring the rest position opposite the stand. 18. Circuit arrangement according to claim 17, characterized in that that a follow-up control is provided when the motor is stopped in a follow-up program carries out the positioning. 19 · Circuit arrangement according to claim 18, characterized in that that for the Posxtionierungsvorgang in at least :. 6664 At least two phase lines transistors (T-, T,) are provided, one after the other for about 0.5 seconds each. conductive being controlled. 20. Circuit arrangement according to one of claims 17 to 19 »characterized in that to initiate the positioning process at least one additional contact, e.g. seat or door contact, is provided.